For example, in a manufacturing process of a semiconductor device, photolithography processing is performed in which a resist coating treatment of applying a resist solution onto, for example, a semiconductor wafer (hereinafter, referred to as a “wafer”) to form a resist film, exposure processing of exposing the resist film to a predetermined pattern, a developing treatment of developing the exposed resist film and so on are performed in sequence to form a predetermined resist pattern on the wafer. Then, using the resist pattern as a mask, an etching treatment is performed on a film to be treated on the wafer and a removal treatment of the resist film is then performed, to form a predetermined pattern in the film to be treated.
Incidentally, miniaturization of the above-described pattern of the film to be treated is required in recent years for higher integration of the semiconductor device. Therefore, miniaturization of the resist pattern is in progress and, for example, the wavelength of light for the exposure processing in the photolithography processing is being reduced. However, there are technical and cost limits in reducing the wavelength of an exposure light source, and it is now difficult to form a fine resist pattern at a level of, for example, several nanometers only by the method of increasingly reducing the wavelength of light.
Hence, there is a proposed wafer treatment method using a block copolymer composed of two kinds of polymers (Non-Patent Document 1). In this method, first, a resist pattern is formed on an anti-reflection film of the wafer, and then a neutral layer having an intermediate affinity to a hydrophilic polymer and a hydrophobic polymer is formed on the anti-reflection film and the resist pattern. Thereafter, the neutral layer on the resist pattern is removed using the resist pattern as a mask, and then the resist pattern itself is also removed. Thus, a pattern of the neutral layer is formed on the anti-reflection film of the wafer, and then a block copolymer is applied onto the anti-reflection film and the pattern-formed neutral layer. Then, the hydrophilic polymer and the hydrophobic polymer are phase-separated from the block copolymer so that the hydrophilic polymer and the hydrophobic polymer are alternately and regularly arrayed on the neutral layer.
Thereafter, by removing, for example, the hydrophilic polymer, a fine pattern of the hydrophobic polymer is formed on the wafer. Then, using the pattern of the hydrophobic polymer as a mask, an etching treatment of the film to be treated is performed to thereby form a predetermined pattern in the film to be treated.
Incidentally, the pattern formation using the block copolymer is used also when forming a contact hole being a fine through hole for performing wiring between stacked wafers in a three-dimensional integration technology of stacking devices in three dimensions. This contact hole is a columnar hole pattern vertical to the upper surface of the wafer, and is formed by a so-called hole shrink process using the block copolymer.
In the case of forming contact holes by the hole shrink process using the block copolymer, first, columnar hole patterns 601 are formed of a resist film 606 on the wafer, for example, as illustrated in FIG. 23. Then, the block copolymer is applied to the wafer on which the hole patterns 601 are formed. Thereafter, the block copolymer is phase-separated into a hydrophilic polymer and a hydrophobic polymer. Thus, in the hole patterns 601 of the resist film 600 formed on the wafer W, the block copolymer is phase-separated into columnar hydrophilic polymers 602 and cylindrical hydrophobic polymers 603 concentric with the hole patterns 601 as illustrated in FIG. 24 and FIG. 25.
Subsequently, for example, by removing the hydrophilic polymers 602 located inside the concentric circles, hole patterns having a smaller diameter than that of the hole pattern 601 of the resist film 600 are formed of the remaining hydrophobic polymers 603. Then, by performing an etching treatment using the hydrophobic polymers 603 as masks, the contact holes being fine through holes are formed on the wafer.